Trogloraptor is a genus of large spiders found in the caves of southwestern Oregon. It is the sole genus in the familyTrogloraptoridae, and includes only one species, Trogloraptor marchingtoni.[1] These spiders are predominantly yellow-brown in color with a maximum leg span of 3 in (7.6 cm). They are remarkable for having hook-like claws on the raptorial last segments of their legs.

Trogloraptor belongs to one of only three new spider families described since 1990. The specific name is in honor of the amateur cave biologist and deputy sheriff Neil Marchington.

Lead researcher Griswold claimed that Trogloraptor might explain the legends of giant cave spiders in the area. The discovery is also notable because only two other new spider families have been described since 1990. The American arachnologist Norman Platnick commented that it was "...as fascinating to arachnologists as the discovery of a new dinosaur is to paleontologists."[3]

Trogloraptor includes only one species, Trogloraptor marchingtoni, and is the only genus in the monotypic family Trogloraptoridae. It was initially suggested that Trogloraptor was a primitive member of the six-eyed spidersuperfamilyDysderoidea.[2] However, Trogloraptor exhibits several unique features, including primitive respiratory systems, that justify its assignment to a separate family. The family probably diverged from other spiders about 130 million years ago, which would make it another notable relicttaxon from North America.[2][4] A 2014 study based on ribosomal DNA found that Trogloraptor fell outside the Dysderoidea and concluded that it should not be included in this clade.[5]

Additional live specimens recovered in 2010 and 2011 from Oregon were all found deep inside caves. Except for a single juvenile specimen recovered from the understory debris of old growthredwood forests of northwest California, none have been found outside the caves. This specimen has different markings than T. marchingtoni and may represent a new undescribed species.[2]

The family Trogloraptoridae may have had a wider distribution given that redwood forests encompassed a far greater area in North America during the Pliocene (about 5 mya). Other species may still be present in other caves.[4]

Adult Trogloraptor have six eyes and a body length of about 7 to 10 mm (0.28 to 0.39 in) in males and 8 to 10 mm (0.31 to 0.39 in) in females.[2] With its legs outstretched, the spider can reach up to 3 in (7.6 cm) in length.[3]

Trogloraptor spin simple webs with only a few strands, hung from the roofs of caves. Griswold et al. stated that the claws may have a significant function in capturing prey. Similar to the Nelson cave spider of New Zealand (Spelungula cavernicola, a gradungulid), Trogloraptor probably dangle upside down from their webs, snatching at passing flying insects with their claws. However their exact prey remains unknown. Captured live specimens were raised in climate-controlled laboratory conditions in an effort to find out. These specimens were offered moths, crickets and other spiders as food; but these were declined and the specimens starved after two weeks. This may indicate a preference for very specific prey.[2][8]

Like most spiders, Trogloraptor possess venom glands. However, the venom is not known to be harmful to humans. The spiders themselves are very shy and unaggressive. They immediately flee illumination.[4]